Quantitative Standards and Heavy Metals Concentration in the Leaves of Isoberlinia doka from Selected Sites at Zaria, Northern Nigeria Guinea Savanna

Hadiza Bello, Amina Bubba Garba, Tindak Cynthia Samagoro

Keywords: Heavy Metal; Quantitative; Isoberlinia Doka ; Northern Nigeria


Background: Isoberlinia doka is an evergreen hardwood tree with fast regenerating ability, widely distributed in northern Nigeria guinea savannah, exploited mainly for fuel wood and ethnomedicinal uses. Objective: This study evaluated the concentration of five heavy metals in Isoberlinia doka leaves collected from three different activity area such as Botanical garden (A1), farming site at Zango (A2) and along high way (A3). Method: The quantitative data such as moisture content, total ash, acid insoluble ash, water soluble ash, ethanol and water extractives values, foaming index, swelling index, tannin content and bitterness value were determined using standard procedures. The concentration of Fe, Cd, Pb, Zn, and Cu were determined using atomic absorption spectrophometer (AAS). Results: The quantitative data varied significantly among the three locations which were within the limit sets by Africa pharmacopoeia. The heavy metals detected in I. doka leaves from A1, A2, and A3 were in the same magnitude of Fe>Zn> Cu. Cd and Pb were not detected in all the three study site. The mean concentration of heavy metals detected at A1 were Fe (275.5 mg/kg), Zn (31.00 mg/kg), and Cu (8.30 mg/kg), A2 has a metal concentration of Fe (367.5 mg/kg), Zn (24.6 mg/kg) and Cu (5.60 mg/kg while that of A3 were of Fe (539.1 mg/kg), Zn (97.00 mg/kg), and Cu (10.40 mg/kg). Conclusions: All the metal detected were within WHO/FDA normal permissible limit for heavy metal in herbal plant except for Fe and Zn in A3 which were above the limit. Analysis of variance shows variability between the three study sites with significant different at p ≤ 0.05 indicating the availability of some of these metal in I. doka leaves due to environmental pollution.